we sent our cert in about 8 days ago and received the certified mail card back that carnival received it...how long does it take for them to process the certificate does anyone know? How will you know if you have an onboard credit like it is supposed to give you?

They seem to be getting on them pretty quick, of late. I've seen a confirmation that they have been applied within a week. One was one day, another two days. Most in about 5 days. Quicker than it used to be.

You could have used the online form...that is probably faster than mailing them.